You will pay 1 tax on all your income 45,000. The tax is figured on your tax return you file. The $638 taxes taken out of the 401K withdrawals are not the actual tax. Just withholding towards the tax. You will get credit for the withholding on your tax return.
You aren't actually paying the tax when you take the 401k withdrawals. You have taxes withheld like from your paycheck. You still have to enter the whole gross amount 15,000 (before taxes were withheld) with your other income to figure out the total tax (and it may put you into a higher tax bracket) and then the withholding is subtracted from the total tax to figure your refund or tax due. The Gross amount shows up on 1040 line 5a and the taxable amount on 5b. The withholding will show up on 1040 line 25b.
